Police have taken into custody three of the four suspects in the killing of American marine biologist Kent Carpenter.

Philippine National Police public information chief, Col. Allen Rae Co, said in a press conference that the director of the Police Regional Office - Negros Island Region relayed this information to the PNP chief, according to a report by GMA News Online.

"The Regional Director of Police Regional Office NIR (Negros Island Region), Police Brigadier General (Romano) Cardiño, reported to the Chief PNP that they've already arrested three of the four suspects in the killing of the American marine biologists," Co said.

Among those arrested is the alleged gunman, the alleged lookout, and the one who allegedly assaulted Carpenter’s live-in partner sexually.

Carpenter, 73, and his live-in partner were watching television evening on July 12, 2026 when the suspects barged into their home in Barangay Ajong in Sibulan, Negros Oriental.

One of the suspects shot Carpenter in the head.

The Special Investigation Task Group (SITG) is looking at robbery, as well as Carpenter’s work as a marine biologist, as possible motives in the crime.

The suspects allegedly took away money and jewelry from the house.

Carpenter’s work was recognized highly in the scientific and academic communities, particularly his research on coral reefs and marine biodiversity.

His work contributed to the Philippines’ case in the 2016 arbitral ruling on the West Philippine Sea (WPS).